EV Charging Station Transformer: Types, Design and Technical Requirements

Why EV Charging Infrastructure Needs Specialized Transformers

With the continuous increase in global penetration rate of new energy vehicles (EVs), the construction of charging infrastructure has entered an acceleration period. Whether it is public DC fast charging stations, highway charging hubs, or slow charging networks in commercial parks and residential areas, they all rely on a key equipment – a dedicated transformer for electric vehicle charging stations.

As the core node connecting the power grid and charging terminals, EV charging station transformers not only undertake the task of voltage level conversion, but also directly determine charging efficiency, operational stability, safety, and system lifespan.

1.Role of Transformers in EV Charging Stations

1.1 High power density and sustained load capacity

EV charging stations, especially DC fast charging stations, have the following typical characteristics:

• High single pile power (60kW – 350kW)
• Parallel operation of multiple piles
• Long term full load or high load operation

This poses higher requirements for transformers:

• Rated capacity redundancy design
• Stronger short-term overload capacity
• Better heat dissipation structure design

1.2 Frequent impact loads and harmonic effects

The charging process of electric vehicles is not a stable linear load, but a typical nonlinear power electronic load:

• Frequent start stop
• Significant current surge
• High harmonic content (mainly 5th, 7th, and 11th)

Therefore, EV charging station transformers typically require:

• Low loss silicon steel or amorphous alloy iron core
• Strengthen the mechanical strength of the winding
• If necessary, configure K-factor design or harmonic suppression scheme

2.Analysis of commonly used transformer types in EV charging stations

2.1 Dry type Transformer: Preferred for Urban and Commercial Scenarios

The application of dry-type transformers in EV charging stations is becoming increasingly widespread, with main advantages including:

• Oil free design, environmentally friendly and safe
• High fire rating, suitable for densely populated areas
• Low maintenance cost

Typical applications:

• Commercial complex charging station
• underground parking
• Urban public charging station

2.2 Oil immersed Transformer: Stable Selection for High Power Centralized Charging Stations

In high-power scenarios such as highway service areas and logistics parks:

• Oil immersed transformers have stronger heat dissipation capabilities
• Suitable for long-term full load operation
• Single unit capacity can achieve greater capacity

3.Key design points of EV charging station transformers

3.1 Voltage level and system matching

Common configurations include:

• High voltage side: 10kV/11kV/20kV/33kV
• Low voltage side: 400V/480V/690V

When designing, it is necessary to fully consider:

• Local power grid standards
• Input voltage requirements for charging stations
• Compatibility between backend rectification and DC module

3.2 Efficiency and Energy Consumption Control

With the tightening of global energy efficiency regulations, EV charging station transformers are gradually moving towards:

• Low no-load loss
• High operational efficiency
• Compliant with IEC/DOE/EU EcoDesign standards

4.Future Development Trends of EV Charging Station Transformers

Evolution towards high efficiency and low loss

Deep integration with intelligent monitoring systems

Customized design for ultra fast charging (≥ 350kW) scenarios

More modular, easy to expand and maintain

The rapid expansion of electric vehicle charging stations has upgraded transformers from “supporting equipment” to “system core”. Choosing the appropriate EV charging station transformer not only affects charging efficiency, but also directly determines the operational reliability and investment return of the entire charging station.

Luoyang Datang Energy Technology Co., Ltd. is a high-tech enterprise integrating R&D, manufacturing and supply of power equipment such as transformers, new energy components, distribution cabinets and inverters. With technological innovation as the core, we focus on creating high-reliability and high-performance power solutions to serve global customers. With a strict quality control system and international standard certification, we continue to output excellent products and enable customers to build safe and stable power systems.